Mount the .dmg and drag the 'SidebarSmartFolders.icns' to the 'Drop here - Resources' alias. You'll need to enter an admin password to edit that folder (it links to the package contents of the CoreTypes.bundle within the System/Library folder).

Copy the 'Smart Folders' folder to a sensible storage location.

Add one or more of the smart folders within that folder to your sidebar. The smart folder logo won't appear, and you'll just get the folder name appearing in the sidebar - i.e. a solid divider line.

Notes

This will make all your smart folders in your sidebar lose the smart folder logo.

Keep the 'Originals' folder from the .dmg in case you want to remove this tweak later.

If you use smart folders a lot in the sidebar, there is also the option to use applications.